Currently, under the name of LTE (Long Term Evolution), the 3GPP (3rd Generation Partnership Project) has undertaken a study of a wireless system with a new wireless technology. In that wireless technology, a plurality of communication channels are defined on a frequency axis and, depending on the communication quality, the communication channels are allocated to terminals for communication purpose. A control channel is used to notify each terminal of channel information regarding allocated communication channels prior to actual data transmission. In Nonpatent Literature 1 mentioned below, downlink channel allocation information is described in Table 7.1.1.2.3.1-1 of Chapter 7.1.1.2.3.1, while uplink channel allocation information is described in Table 7.1.1.2.3.2-1 of Chapter 7.1.1.2.3.2 as part of control information (Resource assignment).
Although it is possible to allocate a plurality of communication channels to a single terminal in the wireless system, the 3GPP is yet to make a decision about the method of notifying channel allocation. For example, in Nonpatent Literature 2 mentioned below, a method of notifying channel allocation with the use of bitmaps is described in the upper portion of FIG. 1. That method is described with reference to FIG. 11. In FIG. 11, a channel allocating station 101 allocates communication channels to terminals 102-1, 102-2, and 102-3. Control information 103-1, 103-2, and 103-3 is channel allocation information transmitted to the terminals 102-1, 102-2, and 102-3, respectively.
The channel allocating station 101 performs channel allocation and transmits channel information to each of the terminals 102-1, 102-2, and 102-3 by using a control channel. According to a bit map method described in Nonpatent Literature 2 mentioned below, the channel allocating station 101 assigns “1” only to the bits that correspond to allocated communication channels and “0” to the remaining bits, and transmits the channel information. Subsequently, each of the terminals 102 determines whether a communication channel corresponding to a bit having “1” in the corresponding channel information is the communication channel allocated thereto. Although not shown in FIG. 11, in practice, the control information corresponding to each terminal includes a terminal number. Thus, by detecting the corresponding terminal number, each terminal can determine the control information intended for itself.
Nonpatent Literature 1: 3GPP, “TR25.814 V7.0.0”, 2006
Nonpatent Literature 2: 3GPP, “R1-060573”, 2006